Colorectal cancer (CRC) is the third most prevalent cancer in the U.S. (Siegel et al., CA Cancer J Clin. 2014, 64(2):104-17). Cancer stem cells (CSCs) are thought to be resistant to current best practice treatments and believed to contribute to tumor metastasis (Ning et al., Cancer Biol Ther. 2013, 14(4):295-303). There is thus a critical need for identifying and selectively targeting CSCs. Several cancer stem cell markers have been identified in literature, including CD44, CD133, Lgr5 and DCLK1 (Park et al., Oncol Rep. 2012, 27(2):339-46; Nomura et al., Oncotarget, 2015, PubMed PMID: 25829252; Schepers et al., Science, 2012, 337(6095):730-5; Kemper et al., Stem Cells, 2012, 30(11):2378-86; May et al., Stem Cells, 2008, 26(3):630-7; Nakanishi et al., Nat Genet. 2013, 45(1):98-103). Besides marking the cancer stem cells, CD44, CD133 and Lgr5 have been reported to play an important functional role in either maintaining the growth of the cancer cells and/or in aiding the metastatic potential of the cells (Park et al., Oncol Rep. 2012, 27(2):339-46; Nomura et al., Oncotarget, 2015, PubMed PMID: 25829252; Schepers et al., Science, 2012, 337(6095):730-5; Kemper et al., Stem Cells, 2012, 30(11):2378-86). More recently, an equally important role of DCLK1 has been implicated in colon tumorigenesis in mice (Nakanishi et al., Nat Genet. 2013, 45(1):98-103; Westphalen et al., J Clin Invest. 2014, 124(3):1283-95; Bailey et al., Gastroenterology. 2014, 146(1):245-56) and in maintaining the proliferative potential of human colon cancer cells (Kantara et al., Cancer Res. 2014, 74(9):2487-98; Sarkar et al., Int J Cancer. 2012, 131(7):E1088-99; Sureban et al., J Nanobiotechnology. 2011, 9:40). It was recently reported that a subset of DCLK1+CSCs were resistant to inhibitory effects of chemopreventive/chemotherapeutic agents, and down-regulation of DCLK1 combined with chemoprevention was required for eliminating CSCs, in vitro and in vivo, and for avoiding relapse (in terms of re-formation of tumorospheres from treated cells) (Kantara et al., Cancer Res. 2014, 74(9):2487-98). These findings highlighted a possible critical role of DCLK1 in maintaining the growth of human colon cancer cell lines, by perhaps protecting the CSC-like populations. Isogenic clones of human embryonic epithelial cells (HEK293), that were either poorly tumorigenic (HEKC) or highly metastatic (HEKmGAS), expressed identical set of stem cell markers, including DCLK1 (Sarkar et al., Int J Cancer. 2012, 131(7):E1088-99). Thus, specifically targeting CSCs has remained a challenge and there remains a need for addition methods for identifying cancerous cells and cancer therapies, particularly for CRC.